Recently, a light emitting diode (LED) is spotlighted as a light emitting device. Since the LED can convert electric energy into light energy with high efficiency and long life span of about 5 years or more, the LED can remarkably reduce the energy consumption and repair and maintenance cost. In this regard, the LED is spotlighted in the next-generation lighting field.
Such an LED is prepared as a light emitting semiconductor layer including a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer, in which the active layer generates light according to current applied thereto through the first and second conductive semiconductor layers.
Meanwhile, since the second conductive semiconductor layer has relatively high sheet resistance due to low carrier concentration and mobility, the LED requires a current spreading layer including ITO (indium tin oxide) or ZnO (zinc oxide) to form an ohmic contact interface with respect to the second conductive semiconductor layer.
In order to allow light generated from the active layer to be emitted to the outside as much as possible, the light extraction efficiency of the LED must be improved. In this regard, research and studies have been performed to form a light extracting structure having a concavo-convex pattern on the second conductive semiconductor layer. However, when the concavo-convex pattern is formed on the second conductive semiconductor layer, electric characteristics of the LED may be degraded.